Photoacoustic thermorelaxation microscopy for thermal diffusivity measurement

Area of Science:

• Materials Science
• Physics
• Optical Engineering

Background:

• Accurate measurement of thermal diffusivity is crucial for understanding material properties.
• Existing techniques for thermal diffusivity measurement often have limitations in resolution or contact requirements.

Purpose of the Study:

• To propose and validate a novel noncontact method for measuring thermal diffusivity using photoacoustic thermorelaxation microscopy.
• To establish a theoretical framework correlating photoacoustic thermorelaxation time with thermal diffusivity.
• To demonstrate the method's applicability across various material types.

Main Methods:

• Utilizing co-focused heating and probing laser pulses with variable time delays.
• Employing photoacoustic detection to monitor in situ thermal relaxation behavior.
• Leveraging the temperature-dependent Grueneisen parameter for signal generation.
• Theoretical modeling to derive the relationship between measured PA thermorelaxation time and thermal diffusivity.

Main Results:

• Theoretical predictions of the PA thermorelaxation time's dependence on thermal diffusivity were established.
• Simulation results showed strong agreement with the theoretical model.
• The method was successfully validated on diverse industrial and biological samples, demonstrating its feasibility.

Conclusions:

• Photoacoustic thermorelaxation microscopy presents a new, noncontact strategy for high-resolution thermal diffusivity measurement.
• The technique offers flexible measurement conditions and shows significant potential for applications in materials science and biology.
• This advancement contributes to the precise characterization of thermo-physical properties in various materials.